What Makes a Quirk?
by Dragonscries
Summary: Ai is an escapee from the League of Villain. With the Quirk, "Ghost," she finds herself haunting Izuku Midoriya, and eventually hiding in plain sight as his Quirk.


**Disclaimer: I don't own BnHA. The writer is a hero; I'm not.**

 **This story was inspired by a lot of other stories. Yesterday Upon the Stair is one. There's also another one, about Izuku having a Quirk that summoned a vigilante named Valkyrie (the name escapes me right now).**

 **I want to see how receptive people are to this idea. If anyone thinks this chapter is poor, I will update this chapter before releasing the next one.**

 **Also, this will remain just one chapter for a week, maybe longer. AP testing is harsh. I've procrastinated enough. That's also why this is short.**

* * *

The League of Villains experiment on her.

In the corner of a dim cell with no door and only one barred window, a little girl curled up in a ball. Forgotten. Or, at least, she wished she was. Horrible scars, some clean and straight, others jagged and stitched together, covered every part of her body - except her face. Not that anyone could see her face, when her black hair always hung over it like a veil.

There was _woosh_ , and a dark hole opened up beneath the girl. She fell through, mouth opened in a scream. Then she was through, and the cell was empty again.

* * *

She ran away. Of course she would run. She hadn't wanted to stay in the cold, dark place with the bird people and white monsters. She was only five years old, and yet she was empty on the inside, stripped of her very identity. But she knew enough to know that the bird people were bad, were unnatural, and if she stayed she would eventually become one of them.

As soon as she became accustomed to the newest modifications they had made to her Quirk, she had realized it was her ticket to escape. The Quirk: Ghost allowed her to manipulate every molecule in her body, letting her turn invisible, intangible, gaseous, hyper-dense, etc. Undoubtedly, the white monsters knew it too, which was why she had to learn how to use the Quirk before they took it away.

When the black mist came to take her, mere minutes after it had dropped her off (probably because some person realized what her Quirk could do), she scraped together what she was capable of doing with her Quirk. She fled, moving through the wall, when the black mist rose up. She hoped that her Quirk would let her phase through the mist. No such luck.

Through the mist was a man, a mask over his face. The man reached out with his had, saying something, but all the girl could hear was her pounding heartbeat and terrified gasps.

The man's hand touched her face, and immediately she was struck by a sense of _wrongness_. She _shouldn't_ touch this... false human, who shouldn't exist, who she knew was cruel and evil and would turn her into a bird person, which she didn't-!

She dissolved, escaping the dark, dark place.

* * *

She didn't know where to go. She was empty, after all. She had no goal, only being driven by the desire to _live._ Because she didn't have money, she had to resort to stealing. One of the first things she stole were clothes - just shorts and a shirt. She sewed her old rags into a tattered black cloak with a hood.

She didn't want to become a bird person, and she didn't trust the police or heroes. If she approached them... the villains would find her. She needed some way to hide.

There was a little family. Two people. A mother and a boy. The mother cooked well. The girl stole bits of leftovers. It wasn't too hard - just wait for the family to finish eating, then turn tangible. And they didn't seem to mind if she slept in their attic. No one would think to find her in an attic, right?

The boy was excited. Too much. It annoyed her to no end. How could this boy be so happy? She had to know.

She followed the boy around. She watched him play with his little Hero figures (and she couldn't be blamed if she also played with them a little when no one was looking, right?). She watched him play with his friend, Kaachan, watched them pretend to be heroes and villains. The boy, Izuku was always the hero, Kaachan always the villain, because honestly, Izuku made a horrible villain. Sometimes, she wished she could join them - but her control over her Quirk was weak, and she found herself only able to remain solid for a few minutes.

She also didn't have a name. If she ever had one, she'd long forgotten it.

* * *

It isn't until she had been following Izuku for half a year when she comes up with a name for herself.

There's a funeral. Someone died in a car crash when a villain rampaged the previous week. The Midoriya family goes. Of course, she follows.

 _Ai._ That's the dead girl's name. She watched as a woman cried. Saying that she would always keep Ai in her heart. A man steps up and adds that she would always love her baby daughter.

She took the name. _Ai. Love._ Because she wanted, no, still wants to be loved by someone. She wants someone to care about her.

Already, she began to consider revealing herself to Izuku and Kaachan. Maybe she had already begun to care for others. She wasn't as empty as before.

* * *

"Hahahaha! Hahahaha! It's fine now! Why? Because I am here!"

Floating and invisible as Izuku watched the video, Ai studied Izuku. His eyes were wide in excitement, and he clutched his All Might figurine in a vice grip. The computer in front of him played a video of a man, carrying several people, yet managing to smile as if nothing was wrong.

 _Does he make you happy, Izuku?_

* * *

She was there when Izuku visited the doctor.

"You should probably give up."

Ai decided that she hated the doctor.

She watched as Izuku cried in his mother's hands. For once, she reached out. Still intangible, she hugged the boy from behind. Her finger solidified for just a moment, to wipe away a tear.

He didn't seem to notice.

* * *

Kaachan changed quickly. Everything about him warped after he got his Quirk, while those changes accelerated after he heard Izuku was Quirkless.

First, he stopped playing "Hero Agency" with Izuku.

"A Quirkless person can't play Hero Agency." He scoffed. His actions troubled Ai at the time. Ai found Izuku playing Hero Agency on his own, pretending to fight an imaginary villain. That was when Ai had an idea.

"Hyah!" he cried, swinging his stick. "I have you now, evil villain!"

"Oh no!" Ai cried, still invisible and intangible, "You got me!"

Izuku froze at the voice. "Wh-wh-who's there?" he stuttered, holding the stick close like a sword. Ai smiled.

"It's me, your imaginary friend!"

Izuku lowered his stuck. "M-my friend?"

"Yup!" Ai responded. "Do you want to play Hero Agency?"

Izuku brightened. "Ok! I want to be All Might!"

As she posed as his imaginary friend, she worried momentarily about Kaachan. A glance showed that he was not alone, surrounded by his own group of friends.

 _Izuku needs me more. Kaachan can handle himself._

* * *

Kaachan's abrasiveness came next. "Get out of the way, side characters," he would say to anyone who tried to confront him. At this point, Ai had definitely grown closer to Izuku than Kaachan. She had already started to dislike the boy. Then again, she was still young, so it made sense that she changed opinions so quickly.

Izuku hadn't shown his imaginary friend to anyone. Maybe it had been because everyone laughed at him. Maybe he had been watching too many cartoons where the main character had some secret that no one believed them about (and he had been watching a couple of those). Maybe it was just because he didn't really have any friends at school anymore, and the distance between him and his mom had grown after Inko had all but admitted that she didn't think Izuku could be a hero.

The first time Kaachan told Izuku to "shove off," Ai had bristled. And yet, despite her not having made a single sound, Izuku had looked straight at her. He had calmed her with that look, that showed that although he was upset, he still respected Kaachan.

* * *

The bullying was the last straw. Kaachan would go around, bullying anyone for any reason - and sometimes for no reason. A year after Izuku's proclaimed Quirklessness, he turned on Izuku.

They were seven at the time (even Ai), when Izuku stood up to Kaachan to protect a boy.

It was recess at school, and they were in a playground when it happened. Bakugou and two more boys had beat up another kid.

"That's mean, Kaachan. C-can't you see he's crying? I-if you keep going-" Izuku stuttered, standing in front of chubby boy who was indeed crying.

"Even though you're Quirkless-" Bakugou smirked, a small explosion erupted as he smashed his palm against his fist, "you're still pretending to be a hero, _Deku?_ "

His first minion charged, devil wings unfurled. Ai acted. Floating above, she turned solid and landed on top of the boy, crushing him - though she did get off quickly, turning intangible, but visible, her body a flickering like a mirage.

"Who-?"

"Ai?" Izuku's eyes widened in surprise. "You're not imaginary?"

An explosion hit her - no, through her, as Kaachan tried to attack her. The heat washed over, and she solidified her fist again and punched him. Or at least, she tried to. Her fist refused to materialize, phasing through Kaachan's face. (AN: see below for explanation)

She immediately retreated, standing in front of Izuku, semi-transparent. Kaachan glared.

"What's this, Deku? You need a girl fighting you fights for you?"

Izuku's eyes flicked between the two. "Ai. Y-you aren't imaginary?"

"No." Ai admitted.

"B-b-but," stuttered the long-fingered boy behind Kaachan, "There's no one in our grade named Ai! Or in our school!"

"Is that so?" explosions bloomed around Kaachan, "So she's from another school? That means she's trespassing!"

"What's going on here?" the teacher walked up to them.

"This girl isn't supposed to be here!" The long-fingered boy said, "She must have broken into the school!"

The man frowned. "It's true that I don't recognize her... Either way!" He straightened. "All of you, come with me! I'm taking you all to the principle to explain why there are two injured boys!"

* * *

"I see." The principle said after listening to Bakugou. "So this girl appeared out of no where, hurt one of your friends, then tried to get in a fight with you?"

"But Bakugou was also-"

"Quiet! I want to hear everyone, one-at-a-time. Now, Ai, can you explain what you were doing? We indeed have no one named Ai at this school."

"I-I-" She scrambled for something to say. She hated attention. If she got in trouble, then all it would take for the villains to find her was a simple glance at this town's records. She was so, so, so scared, and didn't know what to say, and these people had no idea what she was going through because how could they know? What could she say?

"I'm Izuku's Quirk."

* * *

 **Ai's ability is similar to Mirio Togata's. There are some major differences, however.**

 **First, Ai's intangible form is her default form, meaning she has to concentrate to interact with anything. Thus, it's really hard for her to get stronger, since working out is such a hassle for her.**

 **The second is that Ai's Quirk lets her control her molecules. Simply becoming tangible or intangible has no effect on her ability to see, hear, or smell. However, her Quirk also lets her disperse her body, so her body can turn into a liquid or gas. In those states, she can feel objects, but her other senses are gone.**

 **Because her ability involves molecular control, heat can make it difficult for her to become solid. On the other hand, cold can force her into a solid state.**


End file.
